Optical vector multiplier for neural networks

ABSTRACT

An optical vector multiplier can perform linear algebra calculations by using electro-optical modulators of sandwich-type construction or in liquid crystal fields such as occur, inter alia, in the case of neural networks. It can calculate linear algebra operations as rapidly as possible, although the matrix is represented by slow liquid crystal fields. In addition, it can also use the transposed matrix, can calculate the vector product of two vectors and store the resultant matrix of the vector product directly in the region of the matrix modulator cells. To this end, two rapid electro-optical modulators of sandwich-type construction, representing a vector, are disposed offset by 90° and a matrix-shaped optical modulator that represents the matrix follows this arrangement. The vector modulator arrangement that is offset by 90° can form the vector product of two vectors, the result being determined by a detector matrix whose detectors are located on the matrix modulator of each modulator cell. Thus the information can be stored locally there and processed.

CROSS REFERENCE TO RELATED APPLICATION

This application is a national stage of PCT/AT 95/00039 filed 1 Mar.1995 and based upon Austrian National applications A443/94 and A296/95of 2 Mar. 1994 and 17 Feb. 1995, respectively, under the InternationalConvention.

FIELD OF THE INVENTION

My present invention relates to an optical vector multiplier which cancarry out calculations of linear algebra, whereby two light modulatorswith strip-shaped modulator cells representing a vector, are rotated 90°to one another and are arranged in a light path. The light modulatorsare preferably constructed as opto-electronic modulators in a sandwichstructure. The optical vector multiplier can carry out the calculationsof linear algebra, in which the light of a field of individuallycontrollable light sources preferably laser diodes or light diodes,representing a vector is so divided by optical devices that astrip-shaped parallel intensity distribution results.

BACKGROUND OF THE INVENTION

Hitherto, optical computers have been known in which vector matrixmultiplication and the cross product or vector products could becalculated and for which electro-optic modulators or light source fieldswere used. The English Patent GB-A-2 267 165 (SHARP) shows an opticalprocessor which can carry out vector matrix multiplication and also formthe cross product of two vectors with the aid of two light paths. Theresultant matrix of the cross product can be stored in the region of thecells of the matrix modulator. This arrangement has not been howeveruseful in the field of transposed matrices. The European openapplication EP A2-450 526 (HUGHES AIRCRAFT) shows an optical processorwhich can form the cross product of two vectors.

OBJECTS OF THE INVENTION

It is an object of this invention to provide an optical vectormultiplier for a neural network whereby, operations of linear algebracan be calculated as fast as possible, while the matrix is representedby slow liquid crystal fields or by electro-optic modulators whose cellscan only respond serially.

It is another object to provide a multiplier whereby even transposedmatrices can be used in the vector matrix multiplication, the crossproduct of two vectors can be calculated and the resultant matrix of thecross product can be directly stored in the regions of the cells of thematrix modulator.

Still another object allows the light detectors to be distributedoptionally and such that the vector multiplier can operate digitally.

Yet a further object is to provide for the possibility of representingmatrices with negative elements.

Accomplishment of these objects will make the arrangement of theinvention especially suitable for the various models of a neural networkand for use also in a cascade configuration for multi-layer networks.

SUMMARY OF THE INVENTION

These objects are achieved in that an optical multiplier is followed inthe light path by a matrix form or chessboard form light modulator,preferably a liquid crystal modulator, which represents a matrix,whereby selectively there are provided thereon light detectors and/orelectronic circuitry which process the signals from the detectors andcontrol the modulator cells, and reflecting and/or transmittingmodulators are used. The overall modulator arrangement is transluminatedwith parallel light, and the light additionally with the aid of opticaldevices impinges on one or more light detector fields whereby the lightbeams are so deflected that resultant vectors of vector matrixmultiplication and/or vector transposed matrix multiplications can beformed.

Aside from this, the objects are achieved in that a light modulator withstrip-shaped modulator cells representing a vector is provided and thislight modulator is configured preferably as an opto-electronic modulatorin a sandwich construction. The light modulator is arranged in the lightpath rotated through 90° with respect to the strip-like intensitydistribution, this arrangement is followed in the light path by a matrixform or chessboard form light modulator, preferably a liquid crystalmodulator, representing a matrix, whereby selectively there are providedthereon light detectors and/or electronic circuitry which furtherprocesses the signals from the detectors and control the modulatorcells, and reflecting and/or transmitting modulators are used. In thiscase the light then impinges with the aid of optical devices on one ormore light detector fields whereby the light beams are so deflected thatresultant vectors of vector matrix multiplications and/or vector-transposed matrix multiplications can be formed.

The objects can further be achieved in that this arrangement is followedin the light path by a matrix form or chessboard form light modulator,preferably a liquid crystal modulator, representing a matrix, wherebyselectively thereon there are provided light detectors and/or electroniccircuitry which process the signals from the detectors and control themodulator cells and reflecting and/or transmitting modulators are used.In this case the overall modulator arrangement is transluminated withdiffuse light, with light from a light source matrix or with lightpassing through a binary-phase grid or another optical device with amatrix-shaped intensity distribution which, with the aid of lenses orother optical devices is projected upon the respective next modulator.The light can then impinge with the aid of optical devices upon one ormore light detector fields, whereby the light beams are so deflectedthat resultant vectors of vector matrix multiplications and/or vectortransposed matrix multiplications can be formed.

By the 90° rotated arrangement of the vector modulators, one achieveswith one and the same construction both the use of a matrix and also ofthe transposed matrix. All that is necessary is that the respectiveother vector modulator be uniformly transluminated at all rows orcolumns. With the aid of the 90° rotated vector modulator arrangement,the cross product of two vectors can be formed whereby the resultant isdetected by a detector matrix. This detector matrix can also be found onthe chessboard-like optical modulator with each of the individualdetector cells being located in the vicinity of a cell of the matrixmodulator. As a result, the information can be locally stored andprocessed. With this arrangement it is also possible to representvectors and matrices with negative elements whereby the results areobtained by taking the difference between two vector values.

The two detectors capture light beams whose polarization planes arenormal to one another. Additionally it is possible through the use of amatrix-form light deflecting device which can be configured also as ahologram, to optionally space the detectors for the resultant matrix asfar as possible from one another so as to minimize the diffractioneffect. With the optional arrangement of the detectors, digital variantsof the vector multiplier are possible.

BRIEF DESCRIPTION OF THE DRAWING

The above and other objects, features, and advantages will become morereadily apparent from the following description, reference being made tothe accompanying drawing in which:

FIG. 1 is an exploded view which shows the basic structure of theoptical computer unit;

FIG. 2 is a perspective view of the basic arrangement of the lightmodulators;

FIG. 3 is a view similar to FIG. 2 which illustrates a variant with alight source strip;

FIG. 4 is a diagram of a variant which can also operate with negativematrix elements;

FIG. 5 is a plan view of a combination of a matrix modulator and amatrix detector;

FIG. 6 is a diagram which illustrates a variant which operates withdiffused light of a light source matrix or a binary phase grid;

FIG. 7 is a similar diagram which illustrates the principal structure ofthe optical computer unit with a matrix-shaped light deflection device;

FIG. 8 is another diagram which illustrates a variant with a lightsource field;

FIG. 9 is a diagram in the form of an exploded view of a variant whichcan operate with digital vector elements and matrix elements;

FIG. 10 is a plan view which illustrates a 4×4 matrix modulator withmatrix-shaped modulator elements which can display the eight-positiondigital numbers;

FIG. 11 is a plan view illustrates an element of a matrix-shapedmodulator whereby this element is further constructed in a matrix-formfrom a plurality of modulator elements;

FIG. 12 is a diagram similar to FIG. 11 which illustrates a detectorfield showing for each detector the column or line from which lightimpinges;

FIG. 13 is a perspective view from which one sees light paths from thematrix-like light deflection tubes to the detector field;

FIG. 14 is a diagram similar to that of FIG. 13 of a variant is shownwhich comprises holograms as a light-deflecting device; and

FIG. 15 is a plan diagram wherein the detector fields with several lightpoints are illustrated.

SPECIFIC DESCRIPTION

Parallel light, preferably laser light traverses a modulator which isamplitude-modulated in columnar form. This is achieved, for example, bypassing the light initially through a polarizer which polarizes thelight in x' direction, whereby the x' direction is inclined 45° to the xdirection, then through a transverse electro-optical modulator 11, 21(FIGS. 1 and 2) constructed in a sandwich construction and generating aphase modulation of the light row-wise, and then again through apolarizer which stands normal to the x' direction, i.e. in the y'direction. According to this arrangement, one obtains light that isamplitude-modulated row-wise and is polarized in the y' direction.

In FIGS. 1 and 2 only the modulators 11, 12, 21, 22 without thepolarizers have been schematically illustrated. Downstream of thepolarizer, a vector modulator (12, 22) is arranged which is rotated by90° relative to the first modulator, together with a polarizer which ispolarized in the x' direction. This is followed by a checkerboardmodulator 13, 23 whose rows and columns are in agreement with the twovector modulators, and then a polarizer in the y' direction. If thesematrix modulators operate with liquid crystals, the polarization planesof the latter polarizers and the polarization direction ahead of thematrix modulator must be correspondingly matched.

Downstream of the modulator arrangement, a beam divider 14 is providedwhereby the both light beams are focused on two detector rows 16, 17 bytwo cylindrical lenses 15, the detector rows being perpendicular to oneanother with reference to the light path whereby the detector row 16 inthe straight beam is directed either along the x or the y direction.With this arrangement vector matrix multiplication and also vectortransposed matrix multiplication can be carried out. The vectormodulators 11, 12, 21, 22 rotated through 90° , can additionally formthe cross product or vector product of two vectors, the resultant beingrepresented by a matrix-like modulated light beam, which can bedetermined with a vector matrix.

In the arrangement illustrated in FIGS. 1 and 2, these detector matricesare found directly on the matrix modulator 13, 23 so that thesearrangements have the advantage that the respective elements of theproduct matrix are precisely in the place at which a respective cell ofthe matrix modulator is found and the location of which is determined bya detector cell of the detector matrix so that the resultant can therebe locally processed. In FIG. 4 the detector matrix is arranged atanother location, whereby the radiation between the vector modulator andthe matrix modulator is distributed.

The function of the optical computer unit is based upon a two-time localdamping of the light beam, corresponding to an element-wisemultiplication and a collection of light beams by cylindrical lenses,corresponding to a row-wise or column-wise addition. Depending uponwhether a vector matrix multiplication or a vector transposition matrixmultiplication is desired, one of the two vector modulators is madeuniformly light transmissible and the other is controlled correspondingto the vector elements. The associated detector lens combination isnormal to the controlled modulator stack with reference to the lightpath, i.e. the cylindrical axis of the lens and the detector row havethe same direction in the light path as the individual rows of theassociated modulator stack. With the aid of the other modulator stack,respective whole columns or rows of the matrix can be multiplied by afactor should this be required.

A further variant of the optical computing unit is schematicallyillustrated in FIG. 3. In this variant, the first vector modulator isreplaced by a row of light sources 31, for example laser diodes and acylinder lens 35. the vector elements are now described by the intensityof the individual light sources. In this arrangement one must take carethat light beams from neighboring light sources do not fall into thelight paths and thereby falsify the calculation. This can be achievedwith an aid of small lenses which are located ahead of the light sourcesand guarantee that the light is only spread columnwise or row-wise. Thelenses can have diaphragms.

In FIG. 3, the lenses and diaphragms are not shown. With the use of apolarized beam divider, the matrix elements can also be true to sign.The two beam components then contain light rays which, with respect tothe light path, are polarized normal to one another. The beam componentstransit the identical lens detector arrangement 45, 46, 47, and the tworesultant vectors are separated from one another. If the light beamleaves the matrix modulator 43 at 45° relative to the polarizingradiation divider, a zero is represented. Under 0° or 90°, there is anindication of one or minus one.

FIG. 4 shows such an arrangement schematically. The two row modulators41, 42 lie upstream in the light path followed by a radiation divider 44which directs the light path partly through the matrix modulator 43 andpartly onto the product matrix detector 49. Following the matrixmodulator is another beam divider 44 which directs the light into twopolarizing beam dividers 48 which then direct the light into thecorresponding cylinder lenses 45 and row detectors 46, 47. There isadditionally the possibility to use a combination of a modulator matrixand a detector matrix as is illustrated in FIG. 5, which enables a localevaluation of the cross product. Each cell in FIG. 5 contains amodulator 51 and two detectors 52, 53. Negative numbers in the vector,which are applied to the second modulator can be treated by a doubledconfiguration of the second modulator, whereby the absolute values ofthe positive and negative numbers are applied at two neighboring rows,or zeros for positive elements in the row for negative numbers and viceversa.

One of the detectors 52 is then used for the positive numbers and theother 53 for the negative numbers and the modulator cells 51 for bothstates. The corresponding detector rows 16 naturally also must be formedin duplicate and their measurement results correspondingly interpreted.Further, the positive and negative numbers can also be applied in atime-multiplexing process one after another. Another possibility is thatahead of the two detectors and the modulator cells, polarizers can beprovided which allows a second vector with negative elements for thecross product. This method can, however, not be used for vector matrixmultiplication. Additionally, electronic circuitry can be provided inthe individual cells for carrying out logic and memory functions and theresults of the learning process can be read out also in an opticalmanner.

A further variant (FIG. 6) which operates with diffuse light, makes useof a diode matrix 64 or with laser light and a binary phase grid whichgenerates a matrix-form intensity distribution and in which the light isprojected through lenses 65 in the respective next modulator 61, 62, 63,is also conceivable but then the matrix modulator 63 downstream of eachcell must have a microlens and, selectively, diaphragms so that thelight travels as a parallel ray so that it can be deflected in thedetector row.

The optical computer unit illustrated in FIG. 7 operates like theoptical computer unit in FIG. 1 (with the reference numerals in a seriespreceded by the digit "7") whereby the light detectors 75 are notarranged in a line but on a plane, for example, in a matrix form. Sincethese detectors are to be illuminated from light from a single row or asingle column of the matrix modulator, instead of a cylinder lens amatrix from a light-deflecting device 74 must be used. Because of thetwo-dimensional arrangement of the detectors, their spacing must beincreased substantially relative to the one-dimensional arrangement.When, for example, 100 detectors are to be arranged in a matrix form,there is an eleven times greater spacing of the detector center pointswhen the side length of the matrix-form arrangement is equal to thelength of the linear arrangement. In addition, the detectors can also bedistributed three-dimensionally in that they can be applied on an archedsurface or on pedestals to allow the light beams to impinge asperpendicularly run-on as possible. Because of the increase in thespacing, cross-talk to interpreting detectors by light diffractioneffects is reduced.

The diffraction leads to the fact that the light points on the detectorshave a finite expansion so that the spacing of the detector centerpoints cannot be made optionally small. Because of the surfacearrangement of the light points or the detectors, vectors withsubstantially more elements can be worked up and thus the efficiency ofthe computer unit correspondingly increased. Furthermore, this enablesthe formation of inter-mediate results in which a summation in onedetector does not cover an entire row or column but rather only aportion thereof and the further processing is effected electronically.

Corresponding to the subdivision of the rows and columns, a greaternumber of detectors must be provided. The formation of intermediateresults can be of advantage because as a consequence, with the digitalvariants, the sums which result need not be excessive so that they canbe further worked up with precision. With the use of polarizers, withthis variant as well, the matrix elements can be correct as to sign. Thematrix-like light-deflecting device must then generate twice as manybeam components. Then twice as many detectors are required and tworesultant vectors are respectively obtained for the positive andnegative components. The two resultant vectors are also here subtractedfrom one another.

The polarizers can be provided on the matrix-like light-deflectingdevice or also on the detectors. If they are provided on both, this hasthe advantage that there are no interactions between the light of thepositive and of the negative numbers.

The matrix-like light-deflecting device has the purpose of deflectingeach light beam which comes from the matrix modulator to the detectors75, 85 (FIGS. 7 and 8) provided therefor, whereby it should be notedthat both a light beam must impinge upon a detector for the result ofthe vector matrix multiplication and also a further light beam mustimpinge upon a detector for the result of vector-transposed matrixmultiplication. This can be achieved in that each light beam is dividedthrough a combination of a microbeam divider and a microprism anddeflected to the two detectors.

It can also be achieved in that two microprisms can be arranged onebeside the other in each light beam and each microprism can deflect halfthe light beam into the two detectors. Additionally a focusing throughmicrolenses can be effected although this is not required, when thedetectors or the diffraction light points are greater than the lightbeams themselves. Further, for this purpose one can use a field ofholograms or a field of binary or multilevel phase grids. For hologramsit should be noted that, depending on the arrangement, unwanted lightbeams result so that the detectors must be so arranged that these lightbeams are not disturbing.

With holograms, in addition, for each deflected beam, there is also abeam which is deflected with the opposite angle. Aside from this, anondeflected beam is provided and deflection angles of higher order canarise. Binary or multilevel phase grids reduce the undesired lightbeams.

The variant shown in FIG. 8 functions like the variant of FIG. 3,whereby not only the detectors but also the light sources, for example,laser diodes, are oriented in a surface and whereby a three-dimensionalarrangement on arched surfaces or on-pedestal is also possible. In thisvariant, the first vector modulator is replaced by a field of lightsources 81, for example, laser diodes and a matrix-like light-deflectingdevice 86. The vector elements are here represented by the intensity ofthe individual light sources. Ahead of the light sources is to be founda lens field 82 which generates a strip-shaped light distribution on thesubsequent matrix-like light-deflection device 83. From the latter, aparallel matrix-like bundle of light beams is sent out and these lightbeams are subjected to the same processing as the light in the variantof FIG. 7 after the first strip-shaped modulator, i.e. by the elements83, 84 and 85 which correspond to the elements 73, 74 and 75 of FIG. 7.

Further, also here holograms can be used whereby instead of thestrip-shaped pattern, also patterns of light points can abe generated.Thereby ahead of each light source, for example, a binary-phase gridwith micro-optics can be generated which generates a line of lightpoints on the matrix-like light-deflecting device in the correspondingcolumn and which through the light sources can be modulated in theirintensity.

A further variant, which operates with diffused light, with a diodematrix or with laser light and a binary-phase grid generating amatrix-like intensity distribution, is also conceivable in which thelight is projected through the respective next modulator by lenses.However, the matrix modulator then must have after each cell a microlensand selectively diaphragms so that the light runs parallel and can bedeflected in the detector row, whereby these microlenses can also beintegrated in the matrix-like light-deflecting device or embodied as ahologram.

In FIG. 9 a digital variant of the optical vector multiplexer is shownwhereby the matrix-like light-deflecting device is not imaged. Theelements of the matrix-like light-modulator are comprised of smallstrip-shaped modulators for the elements of the matrix 94 and of thetransposed matrix 95, of a field of detectors 96 for the result of thecross product and an optically unused region 97 which, for example, canbe used for electronic circuitry. The strip-shaped modulators havenarrow modulator strips 91 which represent the vector element and widestrips 98 which allow the light to pass unmodulated. These wide stripsare each disposed in the light path ahead of the optically unused regionof the matrix-like modulator.

The modulators in the binary variant switch the light out and in,whereby a binary multiplication with the aid of two modulators connectedone behind the other, can be realized. If another number system is used,then the beam is modulated discretely in multiple stages. A digitalnumber is displayed by a stack of modulators if two such stacks arearranged crossed one behind the other, there results a light beam matrixin which intermediate products of two digital numbers are contained andfor which each requires shifting for addition to yield the final resultof the multiplication of these two numbers. If, with the aid of thedigital variant, the cross product or vector product is formed, theresult is a matrix of matrix-shaped intermediate products which arecollected with the detector field 96. The final result is formed byelectronic processing. Further, the intermediate products can also beoptically added, respectively shifted by one position, in that ahead ofeach detector field a matrix-form light-deflecting device (99) isprovided.

In FIG. 9 for one element this construction has been illustrated. Thisfeature reduces the number of detectors, whereby it should be noted thatin the detectors numerical values arise which are greater than thedigits of the digital numbers. In the same way, intermediate productsare obtained behind the matrix-like modulator in the vector matrixmultiplication and in the vector transposition matrix multiplication.These are added by a light deflection device in an optical mannerwhereby the individual matrices of the intermediate products aresuperimposed or the intermediate products can be added simultaneously ina digit by digit manner. With the next following electronic processingit must be taken into consideration that in detectors numerical valuesarise which are substantially greater than the digits of the digitalnumbers. Negative matrix numbers can be shown also here, as in theanalog variants, by polarizers and doubled detector units. Negativevector elements can be shown through doubled units of the stripmodulators or via a time-multiplex process.

FIG. 10 illustrates a matrix-like modulator of a digital variant wherebythe individual numbers are represented in the matrix-like modulatorelements 101 as is represented equivalently in FIG. 11.

The numbers in the matrix of FIG. 11 are the positions of afour-position digital number. Each position is represented four times,the positions being uniformly diagonal in one direction and increase inthe other direction toward the main diagonal and then begin again withthe first position. With this representation, these modulator cells canbe used both for vector matrix multiplication and for vectortransposition matrix multiplication. A further processing is carried outas in the variant of FIG. 9, whereby the different arrangement of thepositions of the intermediate product is to be noted.

For the formation of the cross product or vector product, also here amatrix-like light deflecting device can be found ahead of the modulatorcells which deflects the light beams directly into the modulator cells102 and with an inclination in the detectors 103 of the cross product.Thus a field of beam dividers or a hologram field can be used, wherebylight paths of higher order, which run to neighboring cells can beinterrupted by diaphragms. If in this embodiment the light is projectedthrough lenses form one modulator to the other, then the light must bemade parallel by a micro-lens field already ahead of the matrix-likelight-deflecting device which is found ahead of the modulator cells.Aside from this, one can omit the matrix-like light-deflecting deviceahead of the modulator cell and for each cell of the modulator element,provide a detector for the cross product whereby the further processingis effected electronically.

In FIG. 12 a detector field is illustrated whereby each detector hasindicated thereon whether light impinges from a row (z) or a column (s)and the number of this row or column. In this example one can see thatthe numeration takes place from opposite sides in a chessboard patternand increases from one side to the other in a row and column manner.With this arrangement signal paths are achieved which are of equallength as much as possible and a reduced angle of spread of light beamsis obtained. In FIG. 13 several light paths form the matrix-likedeflecting device 134 to the detector field 135 are indicated. If ahologram is used then undesired light beams can be detrimental in thisconfiguration.

FIG. 14 shows a variant in which the light deflecting device 144 isformed by a hologram, whereby the detector fields 145 are so arrangedthat undesired light beams do not impinge upon detectors. The desiredlight beams have been drawn in FIG. 14 and the undesired straight linelight beams have been indicated by broken lines. There are still furtherundesired light beams that have not been illustrated to allow thedrawing to be understood. So that additional undesired light beams whicharise from the hologram do not impinge on detectors, the light beamsmust be deflected with large angles. So that the undesired light beamsarise at a multiple of such large angles, the detector fields 145 canhave appropriate places. In both detector fields, the detectors arearranged in a matrix pattern. The light from the left column of thelight-deflecting device is deflected to the detectors on the left sideof the column-detector field and the light from the right column of thelight-deflecting device is deflected to the detectors on the right sideof the column-detector field whereby for each column thelight-deflecting device is provided with at least one detector and thedetectors are illuminated successively from left to right by the columnsof the light-deflecting device.

When one numbers the individual columns of the light-deflecting devicefrom left to right, the respective detectors have numbers which advancein the detector column. For a reproduction of negative signs, the matrixcan be provided, per column of the light-deflecting device, with two andin the case of a digital embodiment, also more detectors. For the rowsof the light-deflecting device there is analogously something. The lightof upper rows are deflected to upper detectors and each lower row tolower detectors of the row-detector field.

In FIG. 15 the detector fields 155 are illustrated from the rear sideout. The light-deflecting device has been represented to show the originof the light beams. In the drawing the light points generated at thedetector field are represented with circles. The light beams come fromelements 151 of the light-deflecting device of the first column and thefirst row. The light point of the straight line light beam isillustrated with a solid circle while the remaining undesired lightpoints are illustrated with thin circles. In FIG. 15, two possibilitiesof the detector illumination have been indicated. In the first, thedetector rows begin the numeration (white circles 152) from the left orin the case of the detector columns from below, whereby in the secondpossibility the light points 156 come closer to the detector field. Forreduction of undesired light points, binary or multi-layer phase gridscan be used. Furthermore, one can use for vector matrix multiplication,vector transposed matrix multiplication and, when necessarydetermination of the sign of the matrix element, various hologramelements whereby each element generates only one desired light point andmuch fewer undesired light points arise. However, with these features,the area of the element is reduced, whereby diffraction effects aregreater. The advantage of the variant in FIG. 14 is that the use ofholograms enables better mass production.

The above described arrangements are suitable predominantly forcalculations of neural networks. With these models, repeated vectormatrix multiplication must be carried out whereby the matrix and itselements change only slowly. The use of rapid electro-optical vectormodules can generate vectors rapidly and the matrix modulator canoperate substantially more slowly. Especially effective results areobtained with the modulator-detector arrangement illustrated in FIG. 5and a construction as in FIG. 4 but without the first beam divider. Ifone provides such arrangements one behind the other, one can achieve anoptical computer for multi-layer neural networks. If the learningprocess is effected by the back-propagation algorithm, the data vector,which normally would contain only positive numbers, is applied to thefirst modulator and the difference vector which also contains negativevalues, to the second modulator.

Simultaneously the calculation is effected with the transposed matrixwhich is compelled by the model. Additionally, the cross product isnecessary in the model and that also can be determined with the aid ofthis device. The result lies just where it is required, namely in thevicinity of the respective modulator cell. The nonlinearities of themodel can be represented by so-called "Look-up" tables whereby even thenonlinear character of the modulators can be considered. Additionally,the vectors must be stored because they will be required later when theback-propagated difference vector is applied to form the cross product.So that the memory and administration costs are held as small aspossible, a vector can be propagated forwardly and a vector propagatedrearwardly in alternation. The changes of the matrix elements can belocally-stored and can be applied to the modulator cells simultaneouslywith or after passage by all vectors.

When cell liquid crystal modulators are used, one must figure on acertain time lag, especially when the changes are simultaneouslyapplied. With changes after the passage of all vectors, one can wait forlapse of the time delay and only then start the next passage. Theresults of the learning process can be then read out. Because of thelocal processing, there is no great cost for wiring and the data can,for example, be inputted and outputted columnwise. As a result, thisoptical computer is suitable also for large networks with in excess of1000 neurons for each completely net layer. If the application of avector takes several nanoseconds, one can have calculating rates ofseveral hundred tera operations per second. If the matrix modulator hasa delay of several microseconds, about 1000 vectors per passage must beapplied so that there will be no noticeable prolongation of thecalculating rate. The optical computer is suitable also for other modelsof a neural network as, for example, the Perceptron, the CompetitiveLearning, the BAM and the Hopfield whereby both first modulators aresuitable for normalization and selection functions of the rows andcolumns and the results from these functions are directly stored in themodulator detector matrix.

I claim:
 1. An optical vector multiplier for calculations of linearalgebra, comprising:two light modulators with strip shaped modulatorcells representing a vector and rotated by 90° relative to one another alight modulator matrix following said light modulators along said path,said matrix comprising a matrix array of light detectors in a pluralityof light detector fields and connected with electronic circuitry forprocessing signals from the detectors, the multiplier being traversed byparallel light and including optical devices causing the light toimpinge upon at least one of said light detector fields, said modulatorarray including modulators for deflecting beams of the light so thatresultant vectors of vector matrix multiplications are formed.
 2. Anoptical vector multiplier for calculations of linear algebra,comprisinga multiplicity of individually controllable light sourcesforming a light field representing a vector; optical devices for shapingsaid field to form a strip-shaped parallel intensity; a light modulatorwith strip-shaped modulator cells representing a vector, the lightmodulator being arranged in a path of the light from said sourcesrotated through 90° relative to the strip-shaped intensity distribution;a light modulator matrix having modulator cells and a matrix arrays oflight detectors in a plurality of light detector fields and connectedwith electronic circuitry which process signals from the detectors andcontrol the modulator cells; and optical devices for deflecting lightbeams onto at least one of said light detector fields so that resultantvectors of vector matrix multiplications are formed.
 3. An opticalvector multiplier for calculations in linear algebra, comprising:twolight modulators with strip-shaped modulator cells representing a vectorand rotated through 90° relative to one another in a light path a lightmodulator matrix downstream of said cells along said path and providedwith an array of modulator cells and light detectors in a plurality offields with electronic circuitry which process signals from thedetectors and control the modulator cells of the arrows, said lightmodulators and said matrix being transluminated with light from a lightsource with a matrix shaped intensity distribution; and optical devicesfor directing the light on at least one of said light detector fields,whereby the light beams are so deflected that resultant detectors ofvector matrix multiplications are formed.
 4. The optical vectormultiplier according to claim 1, claim 2 or claim 3 wherein at least oneof said optical devices is configured as a matrix-like light-deflectingdevices.
 5. The optical vector multiplier according to claim 1, claim 2or claim 3 further comprising a beam divider located ahead of the lightmodulator matrix which deflects the light onto a matrix-like lightdetector field.
 6. The optical vector multiplier according to claim 1,claim 2 or claim 3 elements of said light modulator array areconstructed from strip-shaped modulators representing individualnumbers.
 7. The optical vectifier multiplier defined in claim 1, claim 2or claim 3 wherein said light modulators are optoelectric modulators ina sandwich construction and said light modulator matrix is a liquidcrystalline modulator.